1. Field of the Invention
The present invention relates to horizontal multi-cylinder rotary compressors and, more particularly, it relates to the oil supplying structure of a rotary compressor having multiple cylinders, suitable in refrigerating and air conditioning machines such as a refrigerator, an air conditioner or the like by which power and space are saved less vibration and lower noise are caused, and there is highly reliable.
2. Description of the Related Art
In recent years, compressors to be mounted on refrigerating and air conditioning machines and equipments are required not only to provide fundamental performance with respect to less vibration, lower noise and higher efficiency but also to take up less space and have high reliability. For this reason, a high efficiency rotary compressor is horizontally placed to improve its space-saving characteristic. That is, a horizontal rotary compressor of a single cylinder has been among compressors to be mounted on a conventional refrigerator. Recently, however, development is in progress of a rotary compressor having two cylinders which is efficient in reducing vibrations of the compressor, to respond to the demand in the market for further reduction of vibrations and noise.
A two-cylinder compressor is constructed such that the rotating shaft thereof has two eccentric portions that are different in their phase from each other by 180.degree., so that two rollers fitted on these eccentric portions are eccentrically rotated in the cylinders. Changes in gas compressing torque generated at the two pump units (compressor unit) are thereby leveled off to reduce vibrations of the compressor. For instance, a horizontal rotary compressor having two cylinders such as disclosed in Japanese Utility Model Unexamined Publication No.1-88092 is known as an example of a two-cylinder horizontal rotary compressor.
It is necessary in a horizontal rotary compressor to draw up the lubricating oil reserved at the bottom portion of a sealed container to supply it to the slide portions of the compressor mechanism unit.
FIG. 5 is a cross-sectional view of the main portion of a conventional horizontal single cylinder rotary compressor.
For the oil supplying structure in a single cylinder horizontal rotary compressor, there is an example as shown in FIG. 5 where fluidic diodes 20a, 21 are provided at an inlet side and an outlet side of a vane chamber 14 behind a vane 13 to suck lubricating oil and to thereby supply the lubricating oil to the slide portion of the compressor through an oil supply pipe 22. In the case of a multi-cylinder rotary compressor, however, a problem occurs that the lubricating oil cannot be stably supplied to the compressor mechanism unit by using the conventional oil supplying means shown in FIG. 5, because a plurality of vane chambers are provided.
Further, a description will now be given by way of FIG. 6 with respect to the oil supplying structure of a two-cylinder horizontal rotary compressor as disclosed in Japanese Utility Model Unexamined Publication No.1-88092.
FIG. 6 is a cross sectional view of the main portion of a conventional horizontal two-cylinder rotary compressor.
Referring to FIG. 6, numerals are used to respectively denote: a main bearing 6; a first cylinder 7; a diaphragm 8; a second cylinder 9; a sub-bearing 10; and vane chambers 14, 15.
An oil returning hole 18a for communication between the vane chamber 14 and the motor chamber 16 is provided on a holding plate 19 for separating the interior of the sealed container into a motor chamber 16 and a machine chamber 17, and a backward flow prevention mechanism 24 for preventing a backward flow of the lubricating oil from the machine chamber to the motor chamber is provided on the vane chamber 14. An oil supplying mechanism is thereby achieved such that the lubricating oil sucked to the vane chamber 14 from the motor chamber 16 by the reciprocating movement of the vane 13a is caused to flow to the machine chamber 17 while preventing backward flow of the lubricating oil from the machine chamber 17 to the motor chamber 16.
However, due to such facts as that a valve or the like is additionally necessary behind the vane chamber 14 as the backward flow prevention mechanism 24 and that a separation within the sealed container by the holding plate 19 is necessary, the structure of the compressor becomes complicated, resulting in a problem that its reduction in size is difficult so that it is deprived of space-saving characteristic. Further, in this conventional example, no description has been made with respect to detailed structure of the distributing means by which the lubricating oil supplied to the compressor mechanism unit is distributed to each slide portion.